One of the central dichotomies in theories of cognitive processing is between autonomous theories based on strictly feed forward processing and interactive theories that posit bi-directional flow of information. Speech perception is a particularly interesting battleground for this debate because there is now a vast store of evidence demonstrating lexical level effects on phoneme identification. Some researchers have argued that interactive processing in speech perception is not supported by existing data and that an interactive model is lot consistent with the data. There are three challenges that have not been addressed by the interactive view: lack of lexical inhibition, effects of shifting attention, and lexically mediated phonetic category tuning. The proposed research addresses the lack of lexical inhibition using simulations to show that an interactive model is consistent with the existing data and by experimentally testing predictions from further simulations. A model extension is proposed that adds a mechanism for shifting attention within an interactive framework and proposed experiments test predictions from this mechanism. Finally, proposed simulations test a learning mechanism designed to account for lexically mediated tuning of phonetic categories.